Refrigerant circuit device

ABSTRACT

A refrigerant circuit device includes: a refrigerant circuit including a condenser installed in the storage room, a compressor absorbing and compressing a refrigerant evaporated in the condenser, a heat radiator causing the refrigerant, compressed by the compressor, to release heat from the refrigerant, an electronic expansion valve causing an adiabatic expansion of the refrigerant which has released heat in the heat radiator, and a refrigerant pipe line sequentially connecting the condenser, the compressor, the heat radiator, and the electronic expansion valve to flow the refrigerant; and a controller, in case of performing a forced cooling operation in which the product stored in the storage room is forcedly cooled, adjusting an opening of the electronic expansion valve in a manner that a temperature or a pressure of the refrigerant that has been discharged from the compressor approaches a predetermined target discharge temperature or a predetermined target discharge pressure, respectively.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to and incorporates by referencethe entire contents of Japanese Patent Application No. 2016-222116 filedin Japan on Nov. 15, 2016.

BACKGROUND

The present disclosure relates to a refrigerant circuit device.

In the related art, there has been known a refrigerant circuit deviceused in, for example, an automatic vending machine, the refrigerantcircuit device including a refrigerant circuit which is sequentiallyconnecting a condenser, a compressor, a heat radiator, and an electronicexpansion valve.

A condenser is installed in a product container of the automatic vendingmachine. In the condenser, the supplied refrigerant passes through apredetermined flow channel and evaporates, thereby cooling the internalair of the product container.

The compressor is installed in a machine room that is provided in themain body of the automatic vending machine and outside the productcontainer. The compressor absorbs the refrigerant that has evaporated inthe condenser, and compresses the absorbed refrigerant into ahigh-temperature and high-pressure state and then discharges it.

The heat radiator is installed in the machine room along with thecompressor. The refrigerant that has been compressed by the compressoris guided into the heat radiator, and the refrigerant releases heatthereby heating the ambient air, that is, the refrigerant releases heatin the ambient air.

The electronic expansion valve is installed in the machine room alongwith the compressor and the heat radiator. The electronic expansionvalve decompresses the refrigerant, which has released heat in theradiator, and causes adiabatic expansion of the refrigerant.

In such a refrigerant circuit device, the opening of the electronicexpansion valve is adjusted so that a temperature difference is set to apredetermined value between the evaporating temperature of therefrigerant that flows in the condenser and the temperature inside theproduct container, thereby circulating the refrigerant in therefrigerant circuit to cool the internal air of the product container(see, for example, Japanese Patent No. 5124952).

SUMMARY

According to an embodiment of the present disclosure, a refrigerantcircuit device to cool a product stored in a storage room, includes: arefrigerant circuit including a condenser installed in the storage room,a compressor absorbing and compressing a refrigerant which has beenevaporated in the condenser, a heat radiator causing the refrigerant,which has been compressed by the compressor, to release heat from therefrigerant, an electronic expansion valve causing an adiabaticexpansion of the refrigerant which has released heat in the heatradiator, a refrigerant pipe line sequentially connecting the condenser,the compressor, the heat radiator, and the electronic expansion valve toflow the refrigerant; and a controller, in case of performing a forcedcooling operation in which the product stored in the storage room isforcedly cooled, adjusting an opening of the electronic expansion valvein a manner that a temperature or a pressure of the refrigerant that hasbeen discharged from the compressor approaches a predetermined targetdischarge temperature or a predetermined target discharge pressure,respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view seen from the front illustrating aninternal structure of an automatic vending machine including arefrigerant circuit device according to an embodiment of the presentdisclosure;

FIG. 2 is a cross-sectional side view of a product container present onthe right-hand side of the internal structure of the automatic vendingmachine of FIG. 1;

FIG. 3 is a diagram schematically illustrating the refrigerant circuitdevice according to the embodiment of the present disclosure;

FIG. 4 is a flowchart illustrating a process of operation switchingcontrol performed by a control unit of FIG. 3; and

FIG. 5 is a graphic of a temperature change of the in-containertemperature relative to a product temperature over time.

DETAILED DESCRIPTION

Generally, it is known that a large amount of energy is required forcooling the products when an automatic vending machine including arefrigerant circuit device is installed in a high-temperature andhigh-humidity environment and a forced cooling operation (i.e., a“pull-down operation”) is performed on the products stocked in theproduct container.

Due to the required large amount of energy, the amount of heat requiredin the compressor and the heat radiator also becomes greater accordinglyand the compressor is out of usable range. As a result, the operation ofthe compressor may stop and the forced cooling operation may not beperformed.

In the refrigerant circuit device proposed in Japanese Patent No.5124952, the opening of the electronic expansion valve is adjusted sothat a predetermined temperature difference is set between theevaporating temperature of the refrigerant and the temperature insidethe product container. Due to this, if the automatic vending machineincluding such a refrigerant circuit device is installed in ahigh-temperature and high-humidity environment, there is a risk that theoperation of the compressor stops during the forced cooling operation orthe forced cooling operation cannot be performed.

There is a need for at least partially solving the problems in therelated technology.

A preferred embodiment of a refrigerant circuit device according to thepresent disclosure is described below in detail with reference to theaccompanying drawings.

FIG. 1 is a cross-sectional view seen from the front illustrating aninternal structure of an automatic vending machine, where a refrigerantcircuit device according to the embodiment of the present disclosure isused. The automatic vending machine of FIG. 1 includes a main bodycabinet 1.

The main body cabinet 1 is cuboid in shape and opens at the front face.Inside the main body cabinet 1, two independent product containers(storage rooms) 3 are horizontally arranged in a segmented manner using,for example, a heat insulation divider 2. The product containers 3 areprovided to keep a temperature of the products such as canned drinks orbottled drinks at a desired temperature, and have a heat-insulatedstructure.

FIG. 2 is a cross-sectional side view of a product container present onthe right-hand side of the internal structure of the automatic vendingmachine of FIG. 1. Herein, although the explanation is given about theinternal structure of the product container 3 on the right-hand side(hereinafter, referred to as a “right-side container 3 a”), the productcontainer 3 on the left-hand side (hereinafter, referred to as a“left-side container 3 b”) also has the substantially same internalstructure. Meanwhile, in this written description, the right-hand sideimplies the right-hand side when the automatic vending machine is viewedfrom the front side thereof, and the left-hand side implies theleft-hand side when the automatic vending machine is viewed from thefront side thereof.

As illustrated in FIG. 2, on the front face of the main body cabinet 1,an outer door 4 and an inner door 5 are installed. The outer door 4 isused to open and close the front-side opening of the main body cabinet1, while the inner door 5 is used to open and close the front side ofthe product container 3. The inner door 5 is divided in the verticaldirection, and an upper-side door 5 a is used to open and close tosupply products into the product container 3 at the time of stocking theproducts.

The product container 3 is equipped with a product storage rack 6, adispenser mechanism 7, and a discharging shooter 8 installed therein.The product storage rack 6 is used to store the products along thevertical direction. The dispenser mechanism 7 is disposed below theproduct storage rack 6, and is used to dispense, one by one, theundermost product from among the group of products stored in the productstorage rack 6. The discharging shooter 8 guides the product, which hasbeen dispensed from the dispenser mechanism 7, to a product outlet 4 aprovided in the outer door 4.

FIG. 3 is a diagram schematically illustrating the refrigerant circuitdevice according to the embodiment of the present disclosure. Therefrigerant circuit device of FIG. 3 includes a refrigerant circuit 20,which is filled with carbon dioxide which serves as the refrigerant, anda control unit (controller) 30.

The refrigerant circuit 20 includes a refrigerant pipe line 25 whichsequentially connecting a compressor 21, a heat radiator 22, anelectronic expansion valve 23, and condensers 24.

As illustrated in FIG. 2 as well, the compressor 21 is installed in amachine room 9. Herein, the machine room 9 is provided in the main bodycabinet 1 and on the lower side of the product container 3 and isdivided from the product container 3. The compressor 21 absorbs therefrigerant through a suction inlet, and compresses the absorbedrefrigerant into a high-temperature and high-pressure state (into ahigh-pressure refrigerant) and then discharges it from a spout.

As illustrated in FIG. 2 as well, the heat radiator 22 is installed inthe machine room 9 along with the compressor 21. The heat radiator 22 ismade of aluminum, for example. When the refrigerant that has beencompressed by the compressor 21 passes through the flow channel formedtherein, the heat radiator 22 performs a heat exchange between therefrigerant and the ambient air to release heat.

The electronic expansion valve 23 is installed in the machine room 9along with the compressor 21 and the heat radiator 22. The electronicexpansion valve 23 decompresses the refrigerant passing therethrough andcauses an adiabatic expansion of the refrigerant. Moreover, the openingof the electronic expansion valve 23 is adjusted according toinstructions from the control unit 30.

A plurality of condensers 24 (in the example, only two condensers 24) isprovided, and each condenser 24 is installed in the lower area of thecorresponding product container 3 and on the front side of a backsideduct 10. The condensers 24 are made of aluminum, for example.

The refrigerant pipe line 25 that connects the condensers 24 and theelectronic expansion valve 23 is branched into two pipe lines by adistributor 26 installed in the midway of the refrigerant pipe line 25;and the branched pipe lines are connected to the inlet side of thecondenser 24 installed in the right-side container 3 a (hereinafter,also referred to as a “right-side condenser 24 a”) and the inlet side ofthe condenser 24 installed in the left-side container 3 b (hereinafter,also referred to as a “left-side condenser 24 b”). The condensers 24cause evaporation of the refrigerant passing therethrough, and cool theinternal air of the product containers 3.

In the refrigerant pipe line 25, in the midway of the paths from thedistributor 26 to the condensers 24, there are provided solenoid valves27 a and 27 b and capillary tubes 28 a and 28 b. The solenoid valves 27a and 27 b are openable and closable valving elements that, when aninstruction to open is issued by the control unit 30, open up and allowthe flow of the refrigerant but, when an instruction to close is issued,close and restrict the flow of the refrigerant. The capillary tubes 28 aand 28 b decompress the refrigerant passing therethrough and causeadiabatic expansion of the refrigerant.

The refrigerant pipe lines 25 connected on the outlet side of thecondensers 24 is connected to the compressor 21 in a manner that therefrigerant pipe lines 25 converge at a joining point P and arecommunicated with the suction inlet of the compressor 21.

The symbols “H”, “29”, “F1”, and “F2” in FIG. 3 denote a heater, aninternal heat exchanger, in-container blast fans, and an out-containerblast fan, respectively. The heater H is installed in the left-sidecontainer 3 b, and serves as a heating unit that, when driven to carryelectrical current, heats the internal air of the left-side container 3b. The internal heat exchanger 29 causes a heat exchange between thehigh-pressure refrigerant that has passed through the heat radiator 22and the refrigerant (the low-pressure refrigerant) that has passedthrough the condensers 24. The in-container blast fans F1 are installednear the condensers 24 inside the product containers 3, and serve asin-container blowers that, when driven, blow the internal air of therespective product containers 3. The out-container blast fan F2 isinstalled near the heat radiator 22, and serves as a blower that, whendriven, enables circulation of the external air around the out-containerblast fan F2.

Moreover, in FIG. 3 are also illustrated a discharge temperature sensorS1, evaporating temperature sensors S2, and in-container temperaturesensors S3.

The discharge temperature sensor S1 is installed in the refrigerant pipeline 25 that is communicated to the spout of the compressor 21, anddetects the temperature (the discharge temperature) of the refrigerantdischarged from the compressor 21. The discharge temperature sensor S1sends the detected discharge temperature as a discharge temperaturesignal to the control unit 30.

Evaporating temperature sensors S2 are installed in the respectiverefrigerant pipe lines 25 at the inlet side of the correspondingcondenser 24, and detect the temperatures (the evaporating temperatures)of the refrigerant flowing in the corresponding condensers 24. Theevaporating temperature sensors S2 send the respective detectedevaporating temperature as evaporating temperature signals to thecontrol unit 30.

In-container temperature sensors S3 are installed inside the respectiveproduct containers 3, and detect the internal temperatures (thein-container temperatures) of the corresponding product containers 3.The in-container temperature sensors S3 send the detected in-containertemperatures as in-container temperature signals to the control unit 30.

The control unit 30 comprehensively controls the operations of therefrigerant circuit device according to computer programs and datastored in a memory (not illustrated). The control unit 30 may beintegrated with an automatic-vending-machine control unit (notillustrated) that controls the driving of the automatic vending machine,or may be independently separated from the automatic-vending-machinecontrol unit. Moreover, for example, the control unit 30 may be realizedby causing a processor such as a central processing unit (CPU) toexecute a computer program, that is, may be realized by using software;or may be realized by using hardware such as an integrated circuit (IC);or may be realized by using a combination of software and hardware.

In the refrigerant circuit device having such a configuration asdescribed above, the refrigerant is circulated in the refrigerantcircuit 20 and the products stocked in the product containers 3 arecooled in the following manner. The following explanation is givenregarding the cooling of the internal air of all product containers 3.

In this case, the control unit 30 opens the solenoid valves 27 a and 27b. As a result, the refrigerant that has been compressed by thecompressor 21 reaches the heat radiator 22. Then, the refrigerant thathas reached the heat radiator 22 performs heat exchange with the ambientair (the external air) and releases heat while passing through the heatradiator 22. Subsequently, the refrigerant that has released heat in theheat radiator 22 passes through the internal heat exchanger 29 and thenundergoes adiabatic expansion in the electronic expansion valve 23.

The refrigerant that has undergone adiabatic expansion and turned intogas in the electronic expansion valve 23 is branched in two paths at thedistributor 26; undergoes further adiabatic expansion in the capillarytubes 28 a and 28 b and reaches the right-side condenser 24 a and theleft-side condenser 24 b; evaporates in the condensers 24 and draws heatfrom the internal air of the product containers 3; and thus cools theinternal air. Then, the internal air that has cooled down circulates inthe inside due to the driving of the in-container blast fans F1. As aresult, the products that are stocked in the product containers 3 arecooled by the circulating internal air.

The refrigerant that evaporated in the condensers 24 comes together atthe joining point P and gets absorbed into the compressor 21 via theinternal heat exchanger 29, and then gets compressed in the compressor21 and is again circulated as described above.

In the meantime, in the automatic vending machine, in the case ofperforming the forced cooling operation (the “pull-down operation”) inwhich the products stocked in the product containers 3 are forcedlycooled to a predetermined temperature, the control unit 30 performscontrol to adjust the opening of the electronic expansion valve 23 in amanner that the discharge temperature, which is indicated by thedischarge temperature signal sent from the discharge temperature sensorS1, approaches a predetermined target discharge temperature stored inthe memory or the like. That control is performed usingProportional-Integral-Differential (PID) control, for example. Herein,the target discharge temperature is empirically obtained in view ofmaximizing the cooling capability of the compressor 21.

In the automatic vending machine, in the case of performing a normalcooling operation in which, after the forced cooling operation isperformed, the products stocked in the product containers 3 aremaintained within a cooling temperature range set in advance; if thein-container temperature that is indicated by the in-containertemperature signal sent from each in-container temperature sensor S3becomes equal to or lower than the lower limit temperature of thecooling temperature range, the control unit 30 stops driving thecompressor 21 and, if the in-container temperature becomes equal to orhigher than the upper limit temperature of the cooling temperaturerange, the control unit 30 drives the compressor 21. As a result, atemperature of the products stocked in the product containers 3 aremaintained within the above cooling temperature range.

Moreover, in the case of performing the normal cooling operation, thecontrol unit 30 performs control to adjust the opening of the electronicexpansion valve 23 in a manner that the evaporating temperature, whichis indicated by the evaporating temperature signal sent from eachevaporating temperature sensor S2, approaches a predetermined targetevaporating temperature stored in the memory or the like. That controlis performed using the PID control, for example. Herein, the targetevaporating temperature is empirically obtained in view of achieving anexcellent cooling efficiency.

Moreover, in the case of performing the forced cooling operation, thecontrol unit 30 further performs operation switching control in thefollowing manner. FIG. 4 is a flowchart illustrating a process ofoperation switching control performed by the control unit 30 of FIG. 3.

In the operation switching control, when the in-container temperaturesignals are input from the in-container temperature sensors S3 (Yes inStep S101), the control unit 30 reads a temperature for switching fromthe memory (Step S102). Herein, the temperature for switching refers toa temperature lower than the lower limit temperature of the coolingtemperature range, and is set in a manner that the products stocked inthe product containers 3 have the temperature equal to or lower than theupper limit temperature of the cooling temperature range.

Upon reading the temperature for switching, the control unit 30determines whether the in-container temperature is equal to or lowerthan the temperature for switching (Step S103). If the in-containertemperature is not equal to or lower than the temperature for switching(No in Step S103), the control unit 30 again performs the operationsfrom Steps S101 to S103.

On the other hand, if the in-container temperature is equal to or lowerthan the temperature for switching (Yes in Step S103), then the controlunit 30 switches to the normal cooling operation (Step S104).Subsequently, the system control returns to the start, and theoperations are ended.

FIG. 5 is a graphic of a temperature change of the in-containertemperature relative to a product temperature over time. As illustratedin FIG. 5, as a result of performing the operation switching control, aswitching to the normal cooling operation can be performed at a timing(t1) at which an in-container temperature (A) becomes equal to or lowerthan a temperature for switching (s0), and the temperature of theproducts can be shifted to the intermediate position between a lowerlimit temperature (s1) and an upper limit temperature (s2) within thecooling temperature range.

On the other hand, if the operation switching control is not performedand if the switching to the normal cooling operation is performed at atiming (t2) at which the in-container temperature (A) becomes equal toor lower than the lower limit temperature (s1) of the coolingtemperature range, a product temperature (B) is equal to or higher thanthe upper limit temperature (s2) of the cooling temperature range and,as a result, the product temperature (B) reaches the intermediateposition between the lower limit temperature (s1) and the upper limittemperature (s2) within the cooling temperature range at a timing (t3)that is later than the timing (ti). Thus, by performing the operationswitching control, it becomes possible to shorten the period of timetaken for cooling the products in the cooling temperature range.

As described above, in the refrigerant circuit device according to thepresent embodiment, in the case of performing the forced coolingoperation in which the products stocked in the product containers 3 areforcedly cooled, the control unit 30 adjusts the opening of theelectronic expansion valve 23 in a manner that the discharge temperaturebecomes closer to the target discharge temperature. Hence, even if theautomatic vending machine in which the refrigerant circuit device isimplemented is installed in a high-temperature and high-humidityenvironment, the compressor 21 can be driven at the maximum capabilitythereof and can be prevented from exceeding the usage limits. Since thecompressor 21 can be driven at the maximum capability thereof, theproducts can be cooled in a stable manner. Thus, in the case ofperforming the forced cooling operation in a high-temperature andhigh-humidity environment, the products can be cooled in a successfulmanner.

Besides, in the case of performing a normal cooling operation in whichthe products stocked in the product containers 3 are maintained withinthe cooling temperature range, the control unit 30 controls the openingof the electronic expansion valve 23 in a manner that the evaporatingtemperature approaches the target evaporating temperature. As a result,the products can be cooled by preventing excessive decline in theevaporating temperature, and frost can be prevented from forming on thecondensers 24. Thus, in the case of performing the normal coolingoperation in a high-temperature and high-humidity environment, theproducts can be cooled in a successful manner.

In the refrigerant circuit device, when the in-container temperaturebecomes equal to or lower than the temperature for switching, thecontrol unit 30 switches from the forced cooling operation to the normalcooling operation, thereby enabling shortening of the period of timetaken for cooling the products stocked in the cooling temperature range.

In the refrigerant circuit device, since the condensers 24 are made ofaluminum, they have an excellent heat conductivity. For that reason, inthe case of maintaining the heat-transfer capability equivalent to priorand existing condensers, it becomes possible to increase the inter-pitchdimensions of the fins of the condensers 24. For that reason, even ifthere is frost formation, because of an increase in the inter-pitchdimensions, the flow of air is maintained and the internal air of theproduct containers 3 can be cooled in a successful manner.

Although a preferred embodiment of the present disclosure is described,the present disclosure is not limited to that embodiment and it ispossible to have various modifications.

In the embodiment described above, a case is described where thetemperature (the discharge temperature) of the refrigerant that has beendischarged by the compressor 21 is detected by using the dischargetemperature sensor S1, and the opening of the electronic expansion valve23 is adjusted in accordance with the temperature. Alternatively, in thepresent disclosure, the pressure (the discharge pressure) of therefrigerant discharged by the compressor may be detected, and theopening of the electronic expansion valve can be adjusted in a mannerthat the discharge pressure approaches a target discharge pressure.

In the embodiment described above, a case is described where thetemperature for switching is lower than the lower limit temperature ofthe cooling temperature range and is set in a manner that thetemperature of the product containers 3 becomes equal to or lower thanthe upper limit temperature of the cooling temperature range.Alternatively, in the present disclosure, it is sufficient if thetemperature for switching is lower than the lower limit temperature ofthe cooling temperature range. By doting this as well, it becomespossible to shorten the period of time taken for cooling the products inthe cooling temperature range.

According to the present disclosure, in the case of performing theforced cooling operation in which the products stocked in the storagerooms are forcedly cooled, the controller adjusts the opening of theelectronic expansion valve in a manner that the temperature or thepressure of the refrigerant that has been discharged from the compressorapproaches a predetermined target discharge temperature or apredetermined target discharge pressure, respectively. Hence, even ifthe installation is made in a high-temperature and high-pressureenvironment, the compressor can be driven at the maximum capabilitythereof and can be prevented from exceeding the usage limits. Since thecompressor can be driven at the maximum capability thereof, the productscan be cooled in a stable manner. Thus, in the case of performing theforced cooling operation in a high-temperature and high-humidityenvironment, the products can be cooled in a successful manner.

Moreover, according to the present disclosure, in the case of performingthe normal cooling operation in which the products stocked in thestorage rooms are maintained within a cooling temperature range set inadvance, the controller adjusts the opening of the electronic expansionvalve in a manner that the temperature of the refrigerant that flowsinto the condensers approaches a predetermined target evaporatingtemperature. As a result, the products can be cooled by preventingexcessive decline in the evaporating temperature, and frost can beprevented from forming on the condensers.

Although the invention has been described with respect to specificembodiments for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art that fairly fall within the basic teaching herein setforth.

What is claimed is:
 1. A refrigerant circuit device to cool a productstored in a storage room, the refrigerant circuit device comprising: arefrigerant circuit including a condenser installed in the storage room,a compressor configured to absorb and compress a refrigerant which hasbeen evaporated in the condenser, a heat radiator configured to causethe refrigerant, which has been compressed by the compressor, to releaseheat from the refrigerant, an electronic expansion valve configured tocause an adiabatic expansion of the refrigerant which has released heatin the heat radiator, a refrigerant pipe line sequentially connectingthe condenser, the compressor, the heat radiator, and the electronicexpansion valve to flow the refrigerant; and a controller configured to,in case of performing a forced cooling operation in which the productstored in the storage room is forcedly cooled, adjust an opening of theelectronic expansion valve in a manner that a temperature or a pressureof the refrigerant that has been discharged from the compressorapproaches a predetermined target discharge temperature or apredetermined target discharge pressure, respectively.
 2. Therefrigerant circuit device according to claim 1, wherein, the controlleris configured to, in a case of performing a normal cooling operation inwhich the product stored in the storage room is cooled to havetemperature thereof maintained within a cooling temperature range set inadvance, control the opening of the electronic expansion valve in amanner that a temperature of the refrigerant that flows into thecondenser approaches a predetermined target evaporating temperature. 3.The refrigerant circuit device according to claim 2, wherein, thecontroller is configured to, when an internal temperature of the storageroom is equal to or lower than a temperature for switching which islower than a lower limit temperature of the cooling temperature range,switch from the forced cooling operation to the normal coolingoperation.
 4. The refrigerant circuit device according to claim 3,wherein the temperature for switching is set in a manner that theproduct in the storage room has temperature to be equal to or lower thanan upper limit temperature of the cooling temperature range.
 5. Therefrigerant circuit device according to claim 1, wherein carbon dioxideis used as the refrigerant.